75 lines
1.9 KiB
Go
75 lines
1.9 KiB
Go
// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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package cake_test
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import (
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"testing"
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"time"
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"gopl.io/ch8/cake"
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)
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var defaults = cake.Shop{
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Verbose: testing.Verbose(),
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Cakes: 20,
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BakeTime: 10 * time.Millisecond,
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NumIcers: 1,
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IceTime: 10 * time.Millisecond,
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InscribeTime: 10 * time.Millisecond,
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}
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func Benchmark(b *testing.B) {
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// Baseline: one baker, one icer, one inscriber.
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// Each step takes exactly 10ms. No buffers.
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cakeshop := defaults
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cakeshop.Work(b.N) // 224 ms
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}
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func BenchmarkBuffers(b *testing.B) {
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// Adding buffers has no effect.
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cakeshop := defaults
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cakeshop.BakeBuf = 10
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cakeshop.IceBuf = 10
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cakeshop.Work(b.N) // 224 ms
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}
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func BenchmarkVariable(b *testing.B) {
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// Adding variability to rate of each step
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// increases total time due to channel delays.
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cakeshop := defaults
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cakeshop.BakeStdDev = cakeshop.BakeTime / 4
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cakeshop.IceStdDev = cakeshop.IceTime / 4
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cakeshop.InscribeStdDev = cakeshop.InscribeTime / 4
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cakeshop.Work(b.N) // 259 ms
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}
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func BenchmarkVariableBuffers(b *testing.B) {
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// Adding channel buffers reduces
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// delays resulting from variability.
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cakeshop := defaults
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cakeshop.BakeStdDev = cakeshop.BakeTime / 4
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cakeshop.IceStdDev = cakeshop.IceTime / 4
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cakeshop.InscribeStdDev = cakeshop.InscribeTime / 4
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cakeshop.BakeBuf = 10
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cakeshop.IceBuf = 10
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cakeshop.Work(b.N) // 244 ms
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}
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func BenchmarkSlowIcing(b *testing.B) {
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// Making the middle stage slower
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// adds directly to the critical path.
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cakeshop := defaults
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cakeshop.IceTime = 50 * time.Millisecond
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cakeshop.Work(b.N) // 1.032 s
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}
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func BenchmarkSlowIcingManyIcers(b *testing.B) {
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// Adding more icing cooks reduces the cost of icing
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// to its sequential component, following Amdahl's Law.
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cakeshop := defaults
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cakeshop.IceTime = 50 * time.Millisecond
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cakeshop.NumIcers = 5
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cakeshop.Work(b.N) // 288ms
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}
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